Sony's PlayStation Portable may ultimately live up to company promises of a "Walkman for the 21st century" that revolutionizes entertainment, but that's not going to happen next week.

The electronics giant is set to begin selling the handheld game machine in Japan on Sunday. But the PSP will arrive with a meager selection of games, none of the planned multimedia functions, a history of delays and questions about technical issues such as battery life.

Issues such as those add to Sony's challenges as it not only enters the handheld-game market long dominated by Nintendo, but tries to define a new class of portable entertainment gadget.

"This is a really ambitious thing they're doing, talking about a combination device that's going to have competition from a number of directions," said Brian O'Rourke, an analyst for research company In-Stat/MDR. "It's going to be a real challenge for Sony to educate the market about what this can do."

But the PSP has been a difficult pregnancy, with Sony dogged by development and production issues that look likely to push back the device's North American introduction to late March and limit the Japan launch to 200,000 units.

Game publishers have also pushed back PSP titles, and the console will launch in Japan with only five available games. A Sony Computer Entertainment America spokesman said there are dozens more titles in development, however, and the company "is dedicated to continuing the PlayStation tradition of providing our consumers with the vast library of first- and third-party titles they have grown accustomed to."

A slim opening lineup of games shouldn't be a problem, O'Rourke said, as early adopters will snap up whatever PSP units are available the first few months.

Tackling the tech challenges
"The publicity of having a new product will carry them for a while," he said. "Then they really have to deliver the software."

While the PSP game roster is sure to grow--with dozens of titles in the works by Sony and third-party publishers--promised music and video support is less clear. As of yet, no music or movie studios, including the major ones owned by Sony, have announced plans to release content on the new Universal Media Disc (UMD) optical media format the PSP will use.

The Sony representative said "entertainment software of an entirely new category mixing game, music and video on a single UMD" disc, will be available next spring.

Schelley Olhava, an analyst for research company IDC, said that as long as the PSP has a solid game roster within a reasonable time, Sony can take its time exploiting multimedia capabilities.

"It's going to be like the PlayStation 2: People will buy it because it has games they want to play," Olhava said. "If other stuff happens, they've got time to phase it in."

The PSP will also have to solve some technical challenges, most notably concerns about battery life. Sony estimates that a fully charged PSP battery will be good for four to six hours of game playing.

But Sony Computer Entertainment President Ken Kutaragi acknowledged in a Japanese press interview last month that those estimates were for playing a simple puzzle or card game with the screen dimmed, speakers turned off and wireless connectivity disabled. Turn on all the bells and whistles and load up a graphically complex racing game, and the battery will drain faster. Nintendo's market-leading Game Boy Advance SP, by contrast, runs for more than 10 hours between charges.

The Sony representative said the company was confident the PSP's battery would be sufficient for most owners, but spare battery packs will be available.